<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        /*id选择器*/
        #p1 {color: red}
        /*类选择器*/
        .c1 {color: yellow}
        /*分组选择器*/
        h4,#p1,.c1 {background-color: cornflowerblue}
        /*属性选择器*/
        input[type="text"] {color: darkseagreen}
        /*任意元素选择器*/
        * {border: 1px solid paleturquoise}
    </style>
</head>
<body>
<input type="text">
<input type="password">

<p id="p1">苹果</p>
<p class="c1">香蕉</p>
<p>橘子</p>
<h3>冰箱</h3>
<h3 class="c1">洗衣机</h3>
<h3>空调</h3>
<h4>张三</h4>
</body>
</html>